Cumulative workload comparison between lifting routes of heavy lifting tasks from a biomechanical perspective.

Heavy lifting tasks at work sites can cause musculoskeletal disorders. One strategy to avoid such disorders is to choose a work motion with low cumulative physical workload during the work. This study investigated whether the cumulative workload between different work motions can be compared from a biomechanical perspective. The work motions were analyzed biomechanically by a digital human model. The cumulative workload was calculated using the time integrated value of the product of the torque and the amount of motion at each joint, i.e., an index proposed by a previous study. The results showed that the lifting operation with the shortest route is not always optimal in terms of cumulative workload on the whole body. This indicates the importance of selecting work motions based on a cumulative workload index obtained by mechanical analysis.